Suspension, head gimbal assembly with a multilayered and reinforced suspension and disk drive apparatus with head gimbal assembly

ABSTRACT

A suspension includes a multilayered plate member formed by at least three layers laminated together. The modulus of elasticity of neighboring layers of the at least three layers are different from each other. Both side edges of only a part of the layers of the multilayered plate member within a stiffness-required region are bent to form ribs.

PRIORITY CLAIM

This application claims priority from Japanese patent application No.2003-137340, filed on May 15, 2003, which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a suspension for supporting a flyingtype head slider providing a head element such as a thin-film magnetichead element or an optical head element, to a head gimbal assembly (HGA)with the suspension, and to a disk drive apparatus with the HGA.

2. Description of the Related Art

In a magnetic disk drive apparatus, thin-film magnetic head elements forwriting magnetic information into and/or reading magnetic informationfrom magnetic disks are in general formed on magnetic head slidersflying in operation above the rotating magnetic disks. The sliders aresupported at top end sections of suspensions of HGAs, respectively.

Japanese patent publication 2001-057032A discloses such suspension witha load beam made of a thin stainless steel plate. The load beam hasbends or ribs at its both side ends to enhance the bending stiffness.

For a magnetic disk drive apparatus used in a disk top type computer anda server type computer, a suspension with such structure can be adoptedwithout occurring any problem. This is because such computers areimmovably used, and therefore neither serious impact nor vibration isapplied thereto. Whereas, for a smaller magnetic disk drive apparatuswith a 2.5 inches or less disk to be mainly mounted on a portablecomputer, such suspension is insufficient in the impact resistance dueto insufficient bending stiffness of its load beam.

In order to increase the bending stiffness of the load beam, Japanesepatent publication 2002-352540A proposes using of a multilayered metalsheet made of two metal films bonded by an adhesive or adhering sheet asthe load beam instead of a thin stainless steel plate.

However, even if such multilayered metal sheet is used as the load beam,because of the thin thickness of the metal sheet, it is quite difficultto satisfy the required bending stiffness of the load beam for the 2.5inches or less magnetic disk drive apparatus. If metal sheets with anextremely high thickness are used as for the multilayered metal sheet,relatively high bending stiffness may be expected. However, in thelatter case, the manufacturing cost of the suspension will greatlyincrease.

BRIEF SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide asuspension, an HGA with the suspension, and a disk drive apparatus withthe HGA, whereby a high bending stiffness can be obtained withoutgreatly increasing a manufacturing cost.

According to the present invention, a suspension includes a multilayeredplate member formed by at least three layers laminated together. Themodulus of elasticity of neighbor layers of the at least three layersare different from each other. Both side edges of only a part of thelayers of the multilayered plate member within a stiffness-requiredregion are bent to form ribs.

Conventionally, ribs were not formed in a multilayered suspension withthree or more layers. Whereas, according to the present invention, bothside edges of only a part of the layers of the multilayered suspensionare bent to form ribs. Thus, not only the bending process can beperformed very easy but also sufficient large bending stiffness can beobtained. Particularly, according to the present invention, since it isnot necessary to thicken each layer of the suspension, the total weightof the suspension will not increase and the manufacturing cost can bekept low.

Also, according to the present invention, an HGA includes theabove-mentioned suspension, and a head slider is provided with at leastone head element and mounted on the suspension. A disk drive apparatusaccording to the present invention will have at least one HGA.

It is preferred that both side edges of only a surface layer of themultilayered plate member within a stiffness required region are bent toform ribs.

It is also preferred that both side edges of only a surface layer andits neighbor layer of the multilayered plate member within a stiffnessrequired region are bent to form ribs.

It is preferred that at least one layer of the multilayered plate memberhas a plane shape different from that of the other layer of themultilayered plate member.

It is also preferred that the multilayered plate member includes a firstthin metal plate layer, a resin layer laminated on the first thin metalplate layer, and a second thin metal plate layer laminated on the resinlayer.

It is further preferred that the multilayered plate member includes afirst thin metal plate layer, a second thin metal plate layer laminatedon the first thin metal plate layer and provided with an elasticitycoefficient different from that of the first thin metal plate layer, anda third thin metal plate layer laminated on the second thin metal platelayer and provided with an elasticity coefficient different from that ofthe second thin metal plate layer.

It is still further preferred that the multilayered plate memberincludes a first thin metal plate layer, a first resin layer laminatedon the first thin metal plate layer, a second thin metal plate layerlaminated on the first resin layer, a second resin layer laminated onthe second thin metal plate layer, and a third thin metal plate layerlaminated on the second resin layer.

It is also preferred that the multilayered plate member includes a firstthin metal plate layer, a second thin metal plate layer laminated on thefirst thin metal plate layer and provided with an elasticity coefficientdifferent from that of the first thin metal plate layer, a third thinmetal plate layer laminated on the second thin metal plate layer andprovided with an elasticity coefficient different from that of thesecond thin metal plate layer, a fourth thin metal plate layer laminatedon the third thin metal plate layer and provided with an elasticitycoefficient different from that of the third thin metal plate layer, anda fifth thin metal plate layer laminated on the fourth thin metal platelayer and provided with an elasticity coefficient different from that ofthe fourth thin metal plate layer.

According to the present invention, further, a suspension includes amultilayered plate member formed by at least three layers laminatedtogether, and a reinforced member laminated on only both side edgesections of a surface layer of the multilayered plate member within astiffness required region. Modulus of elasticity of neighbor layers ofthe at least three layers are different from each other.

In a multilayered suspension with three or more layers, a reinforcedmember is laminated on only both side edge sections of a surface layerof the suspension. Thus, sufficient large bending stiffness can beobtained. Particularly, according to the present invention, since it isnot necessary to thicken each layer of the suspension, total weight ofthe suspension will not increase and the manufacturing cost can be keptlow.

Also, according to the present invention, an HGA includes theabove-mentioned suspension, and a head slider provided with at least onehead element and mounted on the suspension. A disk drive apparatusaccording to the present invention will have at least one HGA.

It is preferred that the reinforced member includes a single layerstructure of a thin metal layer or a resin layer.

It is also preferred that the reinforced member includes a multilayeredplate member with a thin metal plate layer and a resin layer laminatedon the thin metal plate layer.

It is also preferred that the reinforced member includes a multilayeredplate member with a first thin metal plate layer, and a second thinmetal plate layer laminated on the first thin metal plate layer andprovided with an elasticity coefficient different from that of the firstthin metal plate layer.

It is preferred that at least one layer of the multilayered plate memberhas a plane shape different from that of the other layer of themultilayered plate member.

It is also preferred that the multilayered plate member includes a firstthin metal plate layer, a resin layer laminated on the first thin metalplate layer, and a second thin metal plate layer laminated on the resinlayer.

It is preferred that the multilayered plate member includes a first thinmetal plate layer, a second thin metal plate layer laminated on thefirst thin metal plate layer and provided with an elasticity coefficientdifferent from that of the first thin metal plate layer, and a thirdthin metal plate layer laminated on the second thin metal plate layerand provided with an elasticity coefficient different from that of thesecond thin metal plate layer.

It is also preferred that the multilayered plate member includes a firstthin metal plate layer, a first resin layer laminated on the first thinmetal plate layer, a second thin metal plate layer laminated on thefirst resin layer, a second resin layer laminated on the second thinmetal plate layer, and a third thin metal plate layer laminated on thesecond resin layer.

It is further preferred that the multilayered plate member includes afirst thin metal plate layer, a second thin metal plate layer laminatedon the first thin metal plate layer and provided with an elasticitycoefficient different from that of the first thin metal plate layer, athird thin metal plate layer laminated on the second thin metal platelayer and provided with an elasticity coefficient different from that ofthe second thin metal plate layer, a fourth thin metal plate layerlaminated on the third thin metal plate layer and provided with anelasticity coefficient different from that of the third thin metal platelayer, and a fifth thin metal plate layer laminated on the fourth thinmetal plate layer and provided with an elasticity coefficient differentfrom that of the fourth thin metal plate layer.

Further objects and advantages of the present invention will be apparentfrom the following description of the preferred embodiments of theinvention as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is an oblique view schematically illustrating main components ofa magnetic disk drive apparatus in a preferred embodiment according tothe present invention;

FIG. 2 is an oblique view illustrating the whole structure of an HGA inthe embodiment of FIG. 1 seen from the side providing with a magnetichead slider,

FIG. 3 is an oblique view illustrating the whole structure of the HGAseen from the opposite side of FIG. 2;

FIG. 4 is an exploded oblique view illustrating a suspension in theembodiment of FIG. 1 seen from the same side of FIG. 2;

FIG. 5 a is an exploded oblique view schematically illustrating thewhole structure of a load beam also serving as a base plate of thesuspension in another embodiment according to the present invention;

FIG. 5 b is an oblique view schematically illustrating a part of a topend section of the load beam shown in FIG. 5 a;

FIG. 6 a is an oblique view illustrating the whole structure of a loadbeam also serving as a base plate of a suspension analyzed by inventorsof this application;

FIG. 6 b is an exploded oblique view of the load beam shown in FIG. 6 a;

FIG. 7 a is an oblique view illustrating the whole structure of a loadbeam also serving as a base plate of a suspension analyzed by theinventors;

FIG. 7 b is an exploded oblique view of the load beam shown in FIG. 7 a;

FIG. 8 a is an oblique view illustrating the whole structure of a loadbeam also serving as a base plate of a suspension analyzed by theinventors;

FIG. 8 b is an exploded oblique view of the load beam shown in FIG. 8 a;

FIG. 9 a is an exploded oblique view schematically illustrating thewhole structure of a load beam also serving as a base plate of thesuspension in further embodiment according to the present invention;

FIG. 9 b is an oblique view schematically illustrating a part of a topend section of the load beam shown in FIG. 9 a;

FIG. 10 a is an exploded oblique view schematically illustrating thewhole structure of a load beam also serving as a base plate of thesuspension in still further embodiment according to the presentinvention;

FIG. 10 b is an oblique view schematically illustrating a part of a topend section of the load beam shown in FIG. 10 a;

FIG. 11 a is an exploded oblique view schematically illustrating thewhole structure of a load beam also serving as a base plate of thesuspension in further embodiment according to the present invention;

FIG. 11 b is an oblique view schematically illustrating the wholestructure of the load beam shown in FIG. 11 a; and

FIG. 11 c is an oblique view schematically illustrating a part of a topend section of the load beam shown in FIG. 11 a.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 schematically illustrates main components of a magnetic diskdrive apparatus in a preferred embodiment according to the presentinvention, FIG. 2 illustrates the whole structure of an HGA in theembodiment of FIG. 1 seen from the side providing with a magnetic headslider, FIG. 3 illustrates the whole structure of the HGA seen from theopposite side of FIG. 2, and FIG. 4 illustrates a suspension in theembodiment of FIG. 1 seen from the same side of FIG. 2.

In FIG. 1, reference numeral 10 denotes a plurality of magnetic harddisks rotating around an axis 11, and 12 denotes an assembly carriagedevice for positioning each magnetic head slider 13 on a track of eachdisk. The assembly carriage device 12 is mainly constituted by acarriage 15 capable of rotating around an axis 14 and an actuator 16such as for example a voice coil motor (VCM) for diving the carnage 15to rotate.

Base sections of a plurality of drive arms 17 stacked along the axis 14are attached to the carriage 15, and one or two HGAs 18 are mounted on atop end section of each arm 17. Each of the HGAs 18 has the magnetichead slider 13 mounted at its top end section so that the slider 13opposes to one surface (recording and reproducing surface) of each ofthe magnetic disks 10.

As shown in FIGS. 2 to 4, the HGA is assembled by fixing a magnetic headslider 21 (13) with a magnetic head element to a top end section of asuspension 20.

The suspension 20 is substantially configured, as shown in FIGS. 2 and3, by a load beam 22, a resilient flexure 23 fixed on the load beam 22,and abase plate 24 fixed to a base section of the load beam 22.

The load beam 22 in this embodiment is obtained by shaping amultilayered plate member. This multilayered plate member is, as clearlyshown in FIG. 4, formed by laminating a first thin metal plate layer 22a such as a stainless steel plate with a thickness of about 51 μm forexample, a resin layer 22 b such as a polyimide resin plate with athickness of about 75 μm for example, and a second thin metal platelayer 22 c such as a stainless steel plate with a thickness of about 51μm for example, in this order from the top.

Particularly, in this embodiment, both side edges of only the first thinmetal plate layer 22 a that is a surface layer (an upper or top surfacelayer or a lower or bottom surface layer in the laminating direction) ofthe load beam are bent toward a direction moving away from the neighborresin layer 22 b to form bending sections or ribs 22 d and 22 e. Theribs 22 d and 22 e at the both side edges are formed only within aregion where high stiffness is required for the load beam 22. No rib isformed in a load generation region 22 f for producing a force to pressthe magnetic head slider 21 toward the magnetic disk surface, and thusthis region 22 f has elasticity.

The flexure 23 has a flexible tongue 23 a depressed by a dimple (notshown) formed on the load beam 22 at its one end section. On the tongue23 a is fixed the magnetic head slider 21. The flexure 23 is made of inthis embodiment a stainless steel thin plate (for example SUS304TA) witha thickness of about 20 μm to have elasticity for supporting flexiblythe magnetic head slider 21 by the tongue 23 a. Fixing of the flexure 23with the load beam 22 and fixing of the load beam 22 with the base plate24 are performed by pinpoint welding at a plurality of points.

In this embodiment, the flexure 23 is fixed to the second thin metalplate layer 22 c of the load beam 22, and the magnetic head slider 21 isfixed on the flexure 23 as aforementioned. Therefore, the ribs 22 d and22 e of the load beam 22 are bent so as to protrude from the surface ofthe suspension 20 opposite to the surface on which the slider 21 ismounted.

The base plate 24 to be attached to the drive arm 17 shown in FIG. 1 ismade of in this embodiment a stainless steel thin plate with a thicknessof about 150 μm.

As for the HGA, a flexible lead conductor member, not shown in FIGS. 2to 4, provided with a plurality of trace conductors in a laminatedthin-film pattern may be formed or attached on the flexure 23. This leadconductor member may be formed by a known method similar to thepatterning method of forming a printed circuit board on a thin metalplate such as a flexible printed circuit (FPC).

Since both side edges of only the first thin metal plate layer 22 a thatis a surface layer (an upper or top surface layer or a lower or bottomsurface layer in the laminating direction) are bent to form the ribs,not only the bending process can be performed very easy but alsosufficient bending stiffness can be obtained even if the load beam isthin. Particularly, according to this embodiment, since it is notnecessary to thicken each layer of the load beam, total weight of thesuspension will not increase and the manufacturing cost can be kept low.

FIG. 5 a schematically illustrates the whole structure of a load beamalso serving as a base plate of the suspension in another embodimentaccording to the present invention, and FIG. 5 b schematicallyillustrates a part of a top end section of the load beam shown in FIG. 5a.

In this embodiment, the load beam has no load generation region forproducing a force to press the magnetic head slider toward the magneticdisk surface, and the whole section of the load beam has a highstiffness. The load force applied to the magnetic head slider will beproduced by some kind of load generation means other thin the load beamin this embodiment.

The load beam 52 in this embodiment is obtained by shaping amultilayered plate member. This multilayered plate member is, as clearlyshown in FIGS. 5 a and 5 b, formed by laminating a first thin metalplate layer 52 a such as a stainless steel plate with a thickness ofabout 51 μm for example, a resin layer 52 b such as a polyimide resinplate with a thickness of about 75 μm for example, and a second thinmetal plate layer 52 c such as a stainless steel plate with a thicknessof about 51 μm for example, in this order from the top.

Particularly, in this embodiment, both side edges of only the first thinmetal plate layer 52 a that is a surface layer (an upper or top surfacelayer or a lower or bottom surface layer in the laminating direction) ofthe load beam are bent toward a direction moving away from the neighborresin layer 52 b to form bending sections or ribs 52 d and 52 e. Theribs 52 d and 52 e at the both side edges are formed along substantiallythe whole region except for a section used for attaching the load beam52 to a drive arm.

The load beam with such structure is formed by bonding sheets 52 a, 52 band 52 c together, which have been preliminarily shaped such that bothside edges of only the surface sheet that corresponds to the first thinmetal plate layer 52 a are outwardly extending in plane, and then bystamping the bonded sheets using for example a stamping die to bend theoutwardly extending side edges of the sheet 52 a. Alternately, the loadbeam may be formed by bonding together sheets 52 a, 52 b and 52 c withthe same shape, then by shaping or by etching for example the bondedsheet so that both side edges of only the surface sheet that correspondsto the first thin metal plate layer 52 a outwardly extends in plane, andthereafter by stamping the sheets using for example a stamping die tobend the outwardly extending side edges of the sheet 52 a.

Since both side edges of only the first thin metal plate layer 52 a thatis a surface layer (an upper or top surface layer or a lower or bottomsurface layer in the laminating direction) are bent to form the ribs,not only the bending process can be performed very easy but alsosufficient bending stiffness can be obtained even if the load beam isthin. Particularly, according to this embodiment, since it is notnecessary to thicken each layer of the load beam, total weight of thesuspension will not increase and the manufacturing cost can be kept low.

Hereinafter, disadvantages of suspension structures analyzed byinventors of this application and advantages of the suspensionstructures according to the present invention will be described indetail.

FIG. 6 a illustrates the whole structure of a load beam also serving asa base plate of a suspension analyzed by the inventors, FIG. 6 billustrates the load beam shown in FIG. 6 a, FIG. 7 a illustrates thewhole structure of a load beam also serving as a base plate of asuspension analyzed by the inventors, FIG. 7 b illustrates the load beamshown in FIG. 7 a, FIG. 8 a illustrates the whole structure of a loadbeam also serving as a base plate of a suspension analyzed by theinventors, and FIG. 8 b illustrates the load beam shown in FIG. 8 a.

As shown in FIGS. 6 a and 6 b, instead of a single stainless steel thinplate, if the load beam is formed by a multilayered plate memberconstituted by only laminating a first thin metal plate layer 62 a, aresin layer 62 b and a second thin metal plate layer 62 c in this orderfrom the top, a sufficient bending stiffness cannot expected due to itssmall thickness. Bending stiffness of the structures of FIGS. 7 a and 7b and FIGS. 8 a and 8 b is analyzed by simulation in comparison with thestructure of FIGS. 6 a and 6 b. In the structure of FIGS. 7 a and 7 b,the load beam is formed by laminating a first thin metal plate layer 72a, a resin layer 72 b with an extremely large thickness, and a secondthin metal plate layer 72 c in this order from the top. In the structureof FIGS. 8 a and 8 b, the load beam is formed by laminating a first thinmetal plate layer 82 a, a resin layer 82 b, and a second thin metalplate layer 82 c in this order from the top, each of the layers 82 a, 82b and 82 c having ribs 82 d and 82 e at its both side edges. In thestructure of FIGS. 6 a and 6 b, each of the first and second thin metalplate layers 62 a and 62 c is constituted by a stainless steel thinplate with a thickness of 51 μm, and a resin layer 62 b is constitutedby an engineering plastic layer with a thickness of 75 μm. In thestructure of FIGS. 7 a and 7 b, each of the first and second thin metalplate layers 72 a and 72 c is constituted by a stainless steel thinplate with a thickness of 51 μm, and a resin layer 72 b is constitutedby an engineering plastic layer with a thickness of 300 μm. In thestructure of FIGS. 8 a and 8 b, each of the first and second thin metalplate layers 82 a and 82 c is constituted by a stainless steel thinplate with a thickness of 51 μm and a resin layer 82 b is constituted byan engineering plastic layer with a thickness of 75 μm.

The results of this simulation are shown in Table 1.

TABLE 1 Primary Primary Secondary Bending Mode Torsion Mode Bending ModeStructure of FIGS. 6a 1428.9 Hz 8703 Hz 6984.3 Hz and 6b Structure ofFIGS. 7a 3451.3 Hz 18547 Hz  15684.0 Hz  and 7b Structure of FIGS. 8a2132.9 Hz 8341 Hz 9536.6 Hz and 8b

As will be understood from Table 1, the structure of FIGS. 6 a and 6 bhas insufficient stiffness because its primary bending mode is less than1500 Hz. On the other hand, the structures of FIGS. 7 a and 7 b andFIGS. 8 a and 8 b have sufficient stiffness because their primarybending mode is over 2000 Hz. However, the structure of FIGS. 7 a and 7b has difficulty in commercialization. This is because the performanceof the suspension is poor due to its heavy weight and the manufacturingcost is greatly increased due to the thick resin layer. Also, sincebending of all of the layers to form the ribs is quite difficult in themanufacturing process, the structure of FIGS. 8 a and 8 b has difficultyin commercialization.

Further, bending stiffness of the structures of this embodiment shown inFIGS. 5 a and 5 b, and also bending stiffness of another embodimentsshown in FIGS. 9 a and 9 b and FIGS. 10 a and 10 b were analyzed bysimulation. Table 2 shows the results of this simulation.

TABLE 2 Primary Primary Secondary Bending Mode Torsion Mode Bending ModeStructure of FIGS. 1994.6 Hz 8801.9 Hz 9425.2 Hz 5a and 5b Structure ofFIGS. 1930.2 Hz 8511.6 Hz 9364.1 Hz 9a and 9b Structure of FIGS. 1975.3Hz 8564.5 Hz 9536.6 Hz 10a and 10b

As will be understood from Table 2, the structure of this embodiment ofFIGS. 5 a and 5 b in which both side edges of only the first thin metalplate layer 52 a that is a surface layer are bent to form the ribs hassufficient bending stiffness because its primary bending mode is near2000 Hz.

The multilayered plate member of the load beam in this embodiment is athree-layer structure consisting of the first thin metal plate layer,the resin layer and the second thin metal plate layer. In modification,however, the multilayered plate member may be a three-layer structureconsisting of a first thin metal plate layer, a second thin metal platelayer made of metal material with a different elasticity coefficientfrom that of the first thin metal plate layer, and a third thin metalplate layer made of metal material with a different elasticitycoefficient from that of the second thin metal plate layer. A thin metalplate made of metal material with a different elasticity coefficientfrom that of the stainless steel thin plate may be for example analuminum thin plate or a titanium thin plate.

In further modification, the multilayered plate member may be afour-layer structure consisting of a first thin metal plate layer, afirst resin layer, a second thin metal plate layer and a second resinlayer, or a four-layer structure consisting of a first thin metal platelayer, a second thin metal plate layer made of metal material with adifferent elasticity coefficient from that of the first thin metal platelayer, a third thin metal plate layer made of metal material with adifferent elasticity coefficient from that of the second thin metalplate layer, and a fourth thin metal plate layer made of metal materialwith a different elasticity coefficient from that of the third thinmetal plate layer.

In still further modification, the multilayered plate member may be afive or more layer structure containing a first thin metal plate layer,a first resin layer, a second thin metal plate layer, a second resinlayer and third thin metal plate layer, or a five or more layerstructure containing a first thin metal plate layer, a second thin metalplate layer made of metal material with a different elasticitycoefficient from that of the first thin metal plate layer, a third thinmetal plate layer made of metal material with a different elasticitycoefficient from that of the second thin metal plate layer, a fourththin metal plate layer made of metal material with a differentelasticity coefficient from that of the third thin metal plate layer,and a fifth in metal plate layer made of metal material with a differentelasticity coefficient from that of the fourth thin metal plate layer.

FIG. 9 a schematically illustrates the whole structure of a load beamalso serving as a base plate of the suspension in further embodimentaccording to the present invention, and FIG. 9 b schematicallyillustrates a part of a top end section of the load beam shown in FIG. 9a.

In this embodiment, the load beam has no load generation region forproducing a force to press the magnetic head slider toward the magneticdisk surface, and the whole section of the load beam has a highstiffness. The load force applied to the magnetic head slider will beproduced by some kind of load generation means other than the load beamin this embodiment.

The load beam 92 in this embodiment is obtained by shaping amultilayered plate member. This multilayered plate member is, as clearlyshown in FIGS. 9 a and 9 b, formed by laminating a first thin metalplate layer 92 a such as a stainless steel plate with a thickness ofabout 51 μm for example, a resin layer 92 b such as a polyimide resinplate with a thickness of about 75 μm for example, and a second thinmetal plate layer 92 c such as a stainless steel plate with a thicknessof about 51 μm for example, in this order from the top.

Particularly, in this embodiment, both side edges of only the secondthin metal plate layer 92 c that is a surface layer (an upper or topsurface layer or a lower or bottom surface layer in the laminatingdirection) of the load beam are bent toward a direction of the neighborresin layer 92 b to form bending sections or ribs 92 d and 92 e. Theribs 92 d and 92 e at the both side edges are formed along substantiallythe whole region except for a section used for attaching the load beam92 to a drive arm.

The load beam with such structure is formed by bonding sheets 92 a, 92 band 92 c together, which have been preliminarily shaped such that bothside edges of only the surface sheet that corresponds to the second thinmetal plate layer 92 c are outwardly extending in plane, and then bystamping the bonded sheets using for example a stamping die to bend theoutwardly extending side edges of the sheet 92 c. Alternately, the loadbeam may be formed by bonding together sheets 92 a, 92 b and 92 c withthe same shape, then by shaping or by etching for example the bondedsheet so that both side edges of only the surface sheet that correspondsto the second thin metal plate layer 92 c outwardly extend in plane, andthereafter by stamping the sheets using for example a stamping die tobend the outwardly extending side edges of the sheet 92 c.

Since both side edges of only the second thin metal plate layer 92 cthat is a surface layer (an upper or top surface layer or a lower orbottom surface layer in the laminating direction) are bent to form theribs, not only the bending process can be performed very easy but alsosufficient bending stiffness can be obtained even if the load beam isthin. Particularly, according to this embodiment, since it is notnecessary to thicken each layer of the load beam, total weight of thesuspension will not increase and the manufacturing cost can be kept low.

As shown in Table 2, the structure of this embodiment of FIGS. 9 a and 9b has sufficient bending stiffness because its primary bending mode isnear 2000 Hz. As will be noted from this Table 2, this structure hassomewhat poor vibration characteristics in comparison with the structureof FIGS. 5 a and 5 b because spaces used for inserting a stamping dieare remained at the inside of the ribs. However, since the space itselfis small, in practice, there occurs no problem.

The multilayered plate member of the load beam in this embodiment is athree-layer structure consisting of the first thin metal plate layer,the resin layer and the second thin metal plate layer. In modification,however the multilayered plate member may be a three-layer structureconsisting of a first thin metal plate layer, a second thin metal platelayer made of metal material with a different elasticity coefficientfrom that of the first thin metal plate layer, and a third thin metalplate layer made of metal material with a different elasticitycoefficient from that of the second thin metal plate layer. A thin metalplate made of metal material with a different elasticity coefficientfrom that of the stainless steel thin plate may be for example analuminum thin plate or a titanium thin plate.

In further modification, the multilayered plate member may be afour-layer structure consisting of a first thin metal plate layer, afirst resin layer, a second thin metal plate layer and a second resinlayer, or a four-layer structure consisting of a first thin metal platelayer, a second thin metal plate layer made of metal material with adifferent elasticity coefficient from that of the first thin metal platelayer, a third thin metal plate layer made of metal material with adifferent elasticity coefficient from that of the second thin metalplate layer, and a fourth thin metal plate layer made of metal materialwith a different elasticity coefficient from that of the third thinmetal plate layer.

In still further modification, the multilayered plate member may be afive or more layer structure containing a first thin metal plate layer,a first resin layer, a second thin metal plate layer, a second resinlayer and third thin metal plate layer, or a five or more layerstructure containing a first thin metal plate layer, a second thin metalplate layer made of metal material with a different elasticitycoefficient from that of the first thin metal plate layer, a third thinmetal plate layer made of metal material with a different elasticitycoefficient from that of the second thin metal plate layer, a fourththin metal plate layer made of metal material with a differentelasticity coefficient from that of the third thin metal plate layer,and a fifth thin metal plate layer made of metal material with adifferent elasticity coefficient from that of the fourth thin metalplate layer.

FIG. 10 a schematically illustrates the whole structure of a load beamalso serving as a base plate of the suspension in still furtherembodiment according to the present invention, and FIG. 10 bschematically illustrates a part of a top end section of the load beamshown in FIG. 10 a.

In this embodiment, also, the load beam has no load generation regionfor producing a force to press the magnetic head slider toward themagnetic disk surface, and the whole section of the load beam has a highstiffness. The load force applied to the magnetic head slider will beproduced by some kind of load generation means other than the load beamin this embodiment.

The load beam 102 in this embodiment is obtained by shaping amultilayered plate member. This multilayered plate member is, as clearlyshown in FIGS. 10 a and 10 b, formed by laminating a first thin metalplate layer 102 a such as a stainless steel plate with a thickness ofabout 51 μm for example, a resin layer 102 b such as a polyimide resinplate with a thickness of about 75 μm for example, and a second thinmetal plate layer 102 c such as a stainless steel plate with a thicknessof about 51 μm for example, in this order from the top.

Particularly, in this embodiment, both side edges of the first thinmetal plate layer 102 a that is a surface layer (an upper or top surfacelayer or a lower or bottom surface layer in the laminating direction)and both side edges of the resin layer 102 b of the load beam are benttoward a direction moving away from the second thin metal plate layer102 c to form bending sections or ribs 102 d and 102 e. The ribs 102 dand 102 e at the both side edges are formed along substantially thewhole region except for a section used for attaching the load beam 102to a drive arm.

The load beam with such structure is formed by bonding sheets 102 a, 102b and 102 c together, which have been preliminarily shaped such thatboth side edges of the surface sheet that corresponds to the first thinmetal plate layer 102 a and both side edges of the sheet thatcorresponds to the resin layer 102 b are outwardly extending in plane,and then by stamping the bonded sheets using for example a stamping dieto bend the outwardly extending side edges of the sheets 102 a and 102b. Alternately, the load beam may be formed by bonding together sheets102 a, 102 b and 102 c with the same shape, then by shaping or byetching for example the bonded sheet so that both side edges of thesurface sheet that corresponds to the first thin metal plate layer 102 aand both side edges of the sheet that corresponds to the resin layer 102b outwardly extend in plane, and thereafter by stamping the sheets usingfor example a stamping die to bend the outwardly extending side edges ofthe sheets 102 a and 102 b.

Since both side edges of only the first thin metal plate layer 102 athat is a surface layer (an upper or top surface layer or a lower orbottom surface layer in the laminating direction) and the resin layer102 b are bent to form the ribs, not only the bending process can beperformed very easy but also sufficient bending stiffness can beobtained even if the load beam is thin. Particularly, according to thisembodiment, since it is not necessary to thicken each layer of the loadbeam, total weight of the suspension will not increase and themanufacturing cost can be kept low.

As shown in Table 2, the structure of this embodiment of FIGS. 10 a and10 b has sufficient bending stiffness because its primary bending modeis near 2000 Hz.

The multilayered plate member of the load beam in this embodiment is athree-layer structure consisting of the first thin metal plate layer,the resin layer and the second thin metal plate layer. In modification,however, the multilayered plate member may be a three-layer structureconsisting of a first thin metal plate layer, a second thin metal platelayer made of metal material with a different elasticity coefficientfrom that of the first thin metal plate layer, and a third thin metalplate layer made of metal material with a different elasticitycoefficient from that of the second thin metal plate layer. A thin metalplate made of metal material with a different elasticity coefficientfrom that of the stainless steel thin plate may be for example analuminum thin plate or a titanium thin plate.

In further modification, the multilayered plate member may be afour-layer structure consisting of a first thin metal plate layer, afirst resin layer, a second thin metal plate layer and a second resinlayer, or a four-layer structure consisting of a first thin metal platelayer, a second thin metal plate layer made of metal material with adifferent elasticity coefficient from that of the first thin metal platelayer, a third thin metal plate layer made of metal material with adifferent elasticity coefficient from that of the second thin metalplate layer, and a fourth thin metal plate layer made of metal materialwith a different elasticity coefficient from that of the third thinmetal plate layer.

In still further modification, the multilayered plate member may be afive or more layer structure containing a first thin metal plate layer,a first resin layer, a second thin metal plate layer, a second resinlayer and third thin metal plate layer, or a five or more layerstructure containing a first thin metal plate layer, a second thin metalplate layer made of metal material with a different elasticitycoefficient from that of the first thin metal plate layer, a third thinmetal plate layer made of metal material with a different elasticitycoefficient from that of the second thin metal plate layer, a fourththin metal plate layer made of metal material with a differentelasticity coefficient from that of the third thin metal plate layer,and a fifth thin metal plate layer made of metal material with adifferent elasticity coefficient from that of the fourth thin metalplate layer.

FIG. 11 a schematically illustrates the whole structure of a load beamalso serving as a base plate of the suspension in further embodimentaccording to the present invention, FIG. 11 b schematically illustratesthe whole structure of the load beam shown in FIG. 11 a, and FIG. 11 cschematically illustrates a part of a top end section of the load beamshown in FIG. 11 a.

In this embodiment, also, the load beam has no load generation regionfor producing a force to press the magnetic head slider toward themagnetic disk surface, and the whole section of the load beam has a highstiffness. The load force applied to the magnetic head slider will beproduced by some kind of load generation means other thin the load beamin this embodiment.

The load beam 112 in this embodiment is obtained by shaping amultilayered plate member and by laminating a reinforced member on themultilayered plate member. The multilayered plate member is, as clearlyshown in FIGS. 11 a, 11 b and 11 c, formed by laminating a first thinmetal plate layer 112 a such as a stainless steel plate with a thicknessof about 51 μm for example, a resin layer 112 b such as a polyimideresin plate with a thickness of about 75 μm for example, and a secondthin metal plate layer 112 c such as a stainless steel plate with athickness of about 51 μm for example, in this order from the top. Thereinforced member has a base section and strip-shaped arm sectionsextending from the base section along respective side edges of themultilayered plate member. These arm sections are laminated on only bothside edge sections of the first thin metal plate layer 112 a that is asurface layer (an upper or top surface layer or a lower or bottomsurface layer in the laminating direction). The reinforced member inthis embodiment is multilayered plate member with a thin metal platelayer 112 f such as a stainless steel plate with a thickness of about 51μm for example and a resin layer 112 g such as a polyimide resin platewith a thickness of about 75 μm for example, laminated in this orderfrom the top.

The reinforced layers 112 f and 112 g at the both side edge sections areformed along substantially the whole region.

The load beam with such structure is formed by bonding sheets 112 a, 112b, 112 c, 112 f and 112 g together, which have been preliminarily shapedsuch that the sheets 112 a, 112 b and 112 c have a required outer shapeand that the arm sections of the reinforced sheets 112 f and 112 gextend along both side edges of the sheets 112 a, 112 b and 112 c.Alternately, the load beam may be formed by bonding together sheets 112a, 112 b, 112 c, 112 f and 112 g with the same shape, then by shaping orby etching for example the bonded sheet so that the sheets 112 a, 112 band 112 c have a required outer shape and that the arm sections of thereinforced sheets 112 f and 112 g extend along both side edges of thesheets 112 a, 112 b and 112 c.

Since the reinforced members 112 f and 112 g are laminated on both sideedge sections, not only the bending process can be omitted but alsosufficient bending stiffness can be obtained even if the load beam isthin. Particularly, according to this embodiment, since it is notnecessary to thicken each layer of the load beam, total weight of thesuspension will not increase and the manufacturing cost can be kept low.

Bending stiffness of the structure of this embodiment shown in FIGS. 11a, 11 b and 11 c was analyzed by simulation. Table 3 shows the resultsof this simulation.

TABLE 3 Primary Primary Secondary Bending Mode Torsion Mode Bending ModeStructure of FIGS. 1933.8 Hz 9182.2 Hz 9704.3 Hz 11a, 11b and 11c

As shown in Table 3, the structure of this embodiment of FIGS. 11 a, 11b and 11 c with the reinforced member 112 f and 112 g laminated on bothside edge sections of the load beam has sufficient bending stiffnessbecause its primary bending mode is near 2000 Hz.

The multilayered plate member of the load beam in this embodiment is athree-layer structure consisting of the first thin metal plate layer,the resin layer and the second thin metal plate layer. In modification,however, the multilayered plate member may be a three-layer structureconsisting of a first thin metal plate layer, a second thin metal platelayer made of metal material with a different elasticity coefficientfrom that of the first thin metal plate layer, and a third thin metalplate layer made of metal material with a different elasticitycoefficient from that of the second thin metal plate layer. A thin metalplate made of metal material with a different elasticity coefficientfrom that of the stainless steel thin plate may be for example analuminum thin plate or a titanium thin plate.

In further modification, the multilayered plate member may be afour-layer structure consisting of a first thin metal plate layer, afirst resin layer, a second thin metal plate layer and a second resinlayer, or a four-layer structure consisting of a first thin metal platelayer, a second thin metal plate layer made of metal material with adifferent elasticity coefficient from that of the first thin metal platelayer, a third thin metal plate layer made of metal material with adifferent elasticity coefficient from that of the second thin metalplate layer, and a fourth thin metal plate layer made of metal materialwith a different elasticity coefficient from that of the third thinmetal plate layer.

In still further modification, the multilayered plate member may be afive or more layer structure containing a first thin metal plate layer,a first resin layer, a second thin metal plate layer, a second resinlayer and third thin metal plate layer, or a five or more layerstructure containing a first thin metal plate layer, a second thin metalplate layer made of metal material with a different elasticitycoefficient from that of the first thin metal plate layer, a third thinmetal plate layer made of metal material with a different elasticitycoefficient from that of the second thin metal plate layer, a fourththin metal plate layer made of metal material with a differentelasticity coefficient from that of the third thin metal plate layer,and a fifth thin metal plate layer made of metal material with adifferent elasticity coefficient from that of the fourth thin metalplate layer.

The reinforced member in this embodiment is a two-layer structureconsisting of the thin metal plate layer and the resin layer. Inmodification, however, the reinforced member may be a two-layerstructure consisting of a first thin metal plate layer and a second thinmetal plate layer made of metal material with a different elasticitycoefficient from that of the first thin metal plate layer. A thin metalplate made of metal material with a different elasticity coefficientfrom that of the stainless steel thin plate may be for example analuminum thin plate or a titanium thin plate. In further modification,the reinforced member may be a three or more layer structure. Also, itis possible to form the reinforced member by a single layer structure ofa thin metal plate layer or a resin layer.

Structure and shape of the suspension of the HGA according to thepresent invention are not limited to the aforementioned structures andshape but various variations can be adopted.

Many widely different embodiments of the present invention may beconstructed without departing from the spirit and scope of the presentinvention. It should be understood that the present invention is notlimited to the specific embodiments described in the specification,except as defined in the appended claims.

1. A suspension comprising: a multilayered plate member formed by atleast three layers laminated together, a modulus of elasticity ofneighboring layers of said at least three layers being different fromeach other and said layers overlapping one another along a lengthportion of each of said layers, said multilayered plate memberconsisting of both side edge sections and a middle section locatedbetween said both side edge sections; and a reinforced member formed byat least one layer and laminated only on said both side edge sections ofa surface layer of said multilayered plate member along an entire lengthportion of said multilayered plate member, wherein no reinforced memberis positioned on said middle section of said multilayered plate member.2. The suspension as claimed in claim 1, wherein said reinforced membercomprises a single layer structure of a thin metal layer or a resinlayer.
 3. The suspension as claimed in claim 1, wherein said reinforcedmember comprises a multilayered plate member with a thin metal platelayer and a resin layer laminated on said thin metal plate layer.
 4. Thesuspension as claimed in claim 1, wherein said reinforced membercomprises a multilayered plate member with a first thin metal platelayer, and a second thin metal plate layer laminated on said first thinmetal plate layer and provided with an elasticity coefficient differentfrom that of said first thin metal plate layer.
 5. The suspension asclaimed in claim 1, wherein at least one layer of said multilayeredplate member has a plane shape different from that of the other layer ofsaid multilayered plate member.
 6. The suspension as claimed in claim 1,wherein said multilayered plate member comprises a first thin metalplate layer, a resin layer laminated on said first thin metal platelayer, and a second thin metal plate layer laminated on said resinlayer.
 7. The suspension as claimed in claim 1, wherein saidmultilayered plate member comprises a first thin metal plate layer, asecond thin metal plate layer laminated on said first thin metal platelayer and provided with an elasticity coefficient different from that ofsaid first thin metal plate layer, and a third thin metal plate layerlaminated on said second thin metal plate layer and provided with anelasticity coefficient different from that of said second thin metalplate layer.
 8. The suspension as claimed in claim 1, wherein saidmultilayered plate member comprises a first thin metal plate layer, afirst resin layer laminated on said first thin metal plate layer, asecond thin metal plate layer laminated on said first resin layer, asecond resin layer laminated on said second thin metal plate layer, anda third thin metal plate layer laminated on said second resin layer. 9.The suspension as claimed in claim 1, wherein said multilayered platemember comprises a first thin metal plate layer, a second thin metalplate layer laminated on said first thin metal plate layer and providedwith an elasticity coefficient different from that of said first thinmetal plate layer, a third thin metal plate layer laminated on saidsecond thin metal plate layer and provided with an elasticitycoefficient different from that of said second thin metal plate layer, afourth thin metal plate layer laminated on said third thin metal platelayer and provided with an elasticity coefficient different from that ofsaid third thin metal plate layer, and a fifth thin metal plate layerlaminated on said fourth thin metal plate layer and provided with anelasticity coefficient different from that of said fourth thin metalplate layer.
 10. A head gimbal assembly comprising: a suspensionincluding a multilayered plate member formed by at least three layerslaminated together, a modulus of elasticity of neighboring layers ofsaid at least three layers being different from each other and saidlayers overlapping one another along a length portion of each of saidlayers, said multilayered plate member consisting of both side edgesections and a middle section located between said both side edgesections, and a reinforced member formed by at least one layer andlaminated only on said both side edge sections of a surface layer ofsaid multilayered plate member along an entire length portion of saidmultilayered plate member, wherein no reinforced member is positioned onsaid middle section of said multilayered plate member; and a head sliderwith at least one head element, said head slider being mounted on saidsuspension.
 11. The head gimbal assembly as claimed in claim 10, whereinsaid reinforced member comprises a single layer structure of a thinmetal layer or a resin layer.
 12. The head gimbal assembly as claimed inclaim 10, wherein said reinforced member comprises a multilayered platemember with a thin metal plate layer and a resin layer laminated on saidthin metal plate layer.
 13. The head gimbal assembly as claimed in claim10, wherein said multilayered plate member comprises a first thin metalplate layer, a resin layer laminated on said first thin metal platelayer, and a second thin metal plate layer laminated on said resinlayer.
 14. A disk drive apparatus with at least one head gimbal assemblycomprising: a suspension including a multilayered plate member formed byat least three layers laminated together, a modulus of elasticity ofneighboring layers of said at least three layers being different fromeach other and said layers overlapping one another along a lengthportion of each of said layers, said multilayered plate memberconsisting of both side edge sections and a middle section locatedbetween said both side edge sections, and a reinforced member formed byat least one layer and laminated only on said both side edge sections ofa surface layer of said multilayered plate member along an entire lengthportion of said multilayered plate member, wherein no reinforced memberis positioned on said middle section of said multilayered plate member;and a head slider with at least one head element, said head slider beingmounted on said suspension.
 15. The disk drive apparatus as claimed inclaim 14, wherein said reinforced member comprises a single layerstructure of a thin metal layer or a resin layer.
 16. The disk driveapparatus as claimed in claim 14, wherein said reinforced membercomprises a multilayered plate member with a thin metal plate layer anda resin layer laminated on said thin metal plate layer.
 17. The diskdrive apparatus as claimed in claim 14, wherein said multilayered platemember comprises a first thin metal plate layer, a resin layer laminatedon said first thin metal plate layer, and a second thin metal platelayer laminated on said resin layer.